1. Field of the Invention
The present general inventive concept relates to an inkjet printhead, and more particularly, to a piezoelectric type inkjet printhead.
2. Description of the Related Art
Generally, inkjet printheads are devices for printing a color image on a printing medium by ejecting droplets of ink onto a desired region of the printing medium. Depending on an ink ejecting method, the inkjet printheads can be classified into two types: electro-thermal transducers (bubble jet type inkjet printheads) and electro-mechanical transducers (piezoelectric type inkjet printheads). The electro-thermal transducers generate bubbles in the ink that is to be ejected by using heat, and eject the ink utilizing the expansion of the bubbles, and the electro-mechanical transducers eject ink by using pressure generated by deforming a piezoelectric material.
FIG. 1 is a cross-sectional view illustrating a normal ink ejection of a conventional piezoelectric type inkjet printhead. FIG. 2 is a cross-sectional view illustrating an abnormal ink ejection of the conventional piezoelectric type inkjet printhead illustrated in FIG. 1.
Referring to FIG. 1, a lower substrate 10 and an intermediate substrate 20 are attached to each other. A damper 21 is formed in the intermediate substrate 20 as a path through which ink flows. A nozzle 11 is formed in the lower substrate 10. The nozzle 11 includes an ink ejecting hole 12 formed on a lower portion of the lower substrate 10, and an ink leading unit 13 formed on an upper portion of the lower substrate 10. Ink is ejected through the ink ejecting hole 12. The ink leading unit 13 connects the damper 21 to the ink ejecting hole 12, and pressurizes and leads ink from the damper 21 into the ink ejecting hole 12.
A bottom surface of the lower substrate 10 is coated with a hydrophobic layer 30, so that the lower substrate 10 is hydrophobic, thereby preventing the ink injecting hole 12 from being wetted by the ejected ink, and stably ejecting an ink drop 15 from the ink injecting hole 12.
The conventional piezoelectric type inkjet printhead finishes ejecting ink, and then performs maintenance for which ink stained around the nozzle 11 is wiped using a wiper 40 that wipes the lower substrate 10 while moving in an arrow direction.
However, as illustrated in FIG. 2, when the wiper 40 wipes and contacts the hydrophobic layer 30 coated around the ink ejecting hole 12, the hydrophobic layer 30 may be removed from the lower substrate 10.
As a result, the possibility of wetting the ink ejecting hole 12 with the ink drop 15 is increased while the hydrophobic layer 30 around the ink ejecting hole 12 is gradually removed by the wiper 40, and thus, the ink drop 15 may be abnormally ejected from the ink ejecting hole 12. In this manner, since an appropriate amount ink can not be ejected on a desired location on a printing medium when the ink drop 15 is abnormally ejected as described-above, the reliability of the conventional piezoelectric type inkjet printhead may be reduced.